Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and a rotor having a rotatable hub with one or more rotor blades. The rotor blades capture kinetic energy of wind using known airfoil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
The rotor blades generally include a suction side shell and a pressure side shell typically formed using molding processes that are bonded together at bond lines along the leading and trailing edges of the blade. Further, the pressure and suction shells are relatively lightweight and have structural properties (e.g., stiffness, buckling resistance and strength) which are not configured to withstand the bending moments and other loads exerted on the rotor blade during operation. Thus, to increase the stiffness, buckling resistance and strength of the rotor blade, the body shell is typically reinforced using one or more structural components (e.g. opposing spar caps with a shear web configured therebetween) that engage the inner pressure and suction side surfaces of the shell halves. The spar caps are typically constructed of various materials, including but not limited to glass fiber laminate composites and/or carbon fiber laminate composites. The shell of the rotor blade is generally built around the spar caps of the blade by stacking layers of fiber fabrics in a shell mold. The layers are then typically infused together, e.g. with a thermoset resin.
Such rotor blades, however, are not without issues. For example, the bond lines of typical rotor blades are generally formed by applying a suitable bonding paste or compound along the bond line with a minimum designed bond width between the shell members. These bonding lines are a critical design constraint of the blades as a significant number of turbine blade field failures occur at the bond-line. Separation of the bond line along the leading and/or trailing edges of an operational turbine blade can result in a catastrophic failure and damage to the wind turbine.
One particular issue that has arisen involves the connection of shear clips to shear webs and spar caps in rotor blades. Shear clips are generally utilized to reinforce the interface between the shear web and spar caps, and are connected to both such components at the shear web-spar cap interface. Because thermoset resins are generally utilized to form such rotor blades, thermoset-based joining techniques such as the application of bonding pastes or hand lay-ups must be utilized to the shear clips to the shear webs and spar caps. It can thus be difficult and time-consuming to join shear clips in rotor blades. Further, in many cases, the shear clips may not completely align with the neighboring shear web and/or spar cap surfaces, due to misalignments and manufacturing tolerances when connecting the shear web and spar caps. Accordingly, the resulting joints between the shear clips and the shear webs and spar caps may be sub-optimal.
Accordingly, improved methods for joining shear clips in wind turbine rotor blades would be advantageous.